The present invention relates to an improved apparatus for transforming water vapor into potable water, and more particularly for obtaining drinking quality water by the formation of condensed water vapor upon a surface maintained at a temperature substantially below the dew point for a given relative humidity condition. The surface upon which the water vapor is condensed is kept below the dew point by means of circulating refrigerant through a closed fluid path which includes refrigerant compression and condensing means.
U.S. Pat. No. 5,301,516 to Poindexter discloses a potable water collection apparatus comprising refrigeration means to maintain a cooling coil at a temperature below the dew point whereby condensed water vapor may form. U.S. Pat. Nos. 5,149,446 and 5,106,512 to Reidy, also disclose refrigeration means to accomplish the same result. Many earlier prior art examples exist within the public domain. However, all of these most recent and previous examples of prior art pose a similar deficiency or shortcoming, specifically, the lack of the ability to cause water vapor to condense in an economical fashion during conditions when the ambient wet bulb and dry bulb temperatures indicate very low relative humidity or less than ideal conditions. The prior art examples, being designed to produce water economically only in an environment containing an ideal temperature and relative humidity, encounter difficulty producing water in an indoor air conditioned environment and consequently they must either be located out of doors or, if located indoors, they must have outside air ducted to them as disclosed in Reidy, U.S. Pat. No. 5,149,446. In U.S. Pat. No. 5,106,512 also to Reidy with reference to FIG. 5, which is a reproduction of a rudimentary psychometric chart, it is disclosed that all water collection takes place at 90 percent relative humidity. What is not revealed by the same illustration is that very little moisture actually exists even at 100 percent relative humidity when the dry bulb temperature is below 65 degrees Fahrenheit (F). In regions where relative humidity averages 20 percent or less year round, regardless of the ambient temperature the dew point is well below the freezing point (32 degrees F). Therefore, while possessing the capability to produce water economically only under the most ideal temperature and relative humidity conditions, for all practical purposes the geographical regions wherein the prior art devices can operate are severely limited. The novel water collection apparatus disclosed herein will overcome these deficiencies and will provide an economical method and means to provide pure unadulterated microbiologically safe drinking water under a wide range of ambient conditions present in differing climatic regions, including regions with conditions which are heretofore considered undesirable for such an apparatus, such as dessert regions. Further, the instant invention will provide an economical means to create pure safe drinking water in regions where water is plentiful yet of undesirable quality or even unsafe to drink, thereby overcoming the shortcoming in the prior art and providing a much needed solution to the water quality problems which exist worldwide in the present day.
It is the object of the present invention to provide a novel means and method for condensing and collecting water for drinking purposes. It is a further object of the invention to provide a highly economical means and method for producing pure drinking water from water vapor. It is yet a further object of the invention to provide a unique departure from conventional refrigeration techniques which are normally employed in water collection apparatus. These and yet further object are fulfilled by employing sophisticated heat and superheat management techniques within a vapor compression refrigeration mechanism. Included within the vapor compression refrigeration component of the invention is a refrigerant de-superheating means further including primary and secondary heat exchange means. During operation, that portion of heat known as superheat is maintained within the system and specifically manipulated in order to create a controlled high relative humidity condition in a region existing at or near the surface of the evaporator component in the vapor compression refrigeration mechanism. The direct result of the manipulation of superheat within the refrigeration system, more specifically the transformation of superheat into latent heat, supplying the latent heat back into the circulating refrigerant, then converting the latent heat again back into superheat, is a high relative humidity condition coincidental with an ideal temperature as well. This novel technique, more accurately described in the detailed description, has the effect of creating the most desirable conditions for the condensation of water vapor during an ambient condition regardless of the prevailing temperature or relative humidity. In addition, the aforementioned novel superheat manipulation technique is accomplished with no adverse effects upon the refrigeration mechanism with respect to entropy or enthalpy, rather providing a positive effect whereby typical pressures are consistently exhibited.
Further included is a means for containing collected water, various operational controls and a germicidal control means.